Snapchat can be way more useful than the casual selfie would have you believe. In fact, one man used the app to launch a full-blown PSA. While donating blood at a local hospital, Mumbai man Aashish Mehrotra felt inspired to send an important message to anyone who would listen: "Stop making it easier for cancer—quit smoking now."

Mehrotra used smoke occasionally, but he stopped after losing a friend to cancer. That's when he went full force and began donating platelets and white blood cells to those in need. "I would see families coming in and out of the oncology department," he told BuzzFeed. "Faces of despair, some of hope, and others of lost hope." It was then he decided to use an everyday social media app to do some good—or at the least, raise awareness.

His story begins with a simple snap. "Let me tell you a story," it reads. "Not necessarily a happy one." What follows is a poignant and emotional narrative about the dangers of cancer. And though it's mostly told through selfies, it's incredibly moving.

Cigarette smoking is the leading preventable cause of death in the U.S., killing 480,000 people annually. And nearly 42,000 of those deaths are thought to be caused by secondhand smoking. Smoking is also linked to 90 percent of lung cancer deaths, as well as increasing the likelihood of having a stroke or developing heart disease.